Atmospheric flight gust loads analysis

Kim, M.; Lee, S.; Kabe, Alvar M.

doi:10.2514/6.1999-1252

“…The program was used to develop 24 sets of forcing functions that were used in the Monte Carlo gust analysis described in Ref. 15. 1 1 1 1 1 1 j 1 1 1 1 1 1 1 1 1 | Tl 11 T I M 1 I 1 1 1 1 1 1 1 1 1 [ 1 1 1 1 1 1 1 1 1 | 1 1 1 1 1 1 1 1 1 3300 '<%?…”

Section: Resultsmentioning

confidence: 99%

Derivation of Forcing Functions for Monte Carlo Atmospheric Gust Loads Analysis

Sako¹,

Kim²,

Kabe³

et al. 1999

0

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Public reporting burden tor this collection of information is estimated to average 1 hour per response, includinq the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden 'to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington. VA 22202-4302, and A methodology developed to derive forcing functions from the turbulent component of measured wind profiles for a new Monte Carlo gust loads analysis approach is described. Several large sets of forcing functions were developed by extracting the short-duration, random component of measured Jimsphere wind profiles. A database consisting of Jimsphere wind soundings measured over the past three decades at the Eastern and Western Ranges of the United States was used to derive the forcing functions. Validity of these forcing functions for heavy-lift and medium-lift launch vehicles was established by examining the error contributions from various sources within the wind measurement system and the application of a noise-reducing filter. A unique aspect of the method is the extraction of the relatively rapidly changing turbulent component associated with the non-persistent wind features which are expected over a given observation time period. SUBJECT TERMS AbstractA methodology is developed to derive gust forcing functions from the turbulent components of measured wind profiles. Several large sets of forcing functions were developed by extracting the short-duration, random component of measured Jimsphere wind profiles. A database consisting of Jimsphere wind soundings measured over the past three decades at the Eastern and Western Ranges of the United States was used to derive the forcing functions. Validity of these forcing functions for heavy-lift and medium-lift launch vehicles was established by examining the error contributions from various sources within the wind measurement system and the application of a noise reducing filter. A unique aspect of the method is the extraction of the relatively rapidly changing turbulent component associated with the non-persistent wind features which are expected over a given observation time period. The gust forcing functions can be used in a Monte Carlo analysis to determine launch vehicle loads for the Eastern and Western Ranges.

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“…15) required each filtered wind profile to be restricted to an altitude band of 6000 ft. To minimize step responses during the gust loads simulations, a flattop window having a ten percent cosine taper at each end was used (Fig. 8c).…”

Section: Restriction To 6000-ft Bandsmentioning

confidence: 99%

“…a) Two-point smoothed wind and trend removed for X G = 4200 ft; b) High-passed filtered wind profile 33 15. a) Two-point smoothed wind and trend removed for X G = 4700 ft; b) High-passed filtered wind profile 34 16.…”

mentioning

confidence: 99%

Derivation of forcing functions for Monte Carlo atmospheric gust loads analysis

Sako

¹

,

Kim

²

,

Kabe

³

et al. 1999

40th Structures, Structural Dynamics, and Materials Conference and Exhibit

Self Cite

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Public reporting burden tor this collection of information is estimated to average 1 hour per response, includinq the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden 'to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington. VA 22202-4302, and A methodology developed to derive forcing functions from the turbulent component of measured wind profiles for a new Monte Carlo gust loads analysis approach is described. Several large sets of forcing functions were developed by extracting the short-duration, random component of measured Jimsphere wind profiles. A database consisting of Jimsphere wind soundings measured over the past three decades at the Eastern and Western Ranges of the United States was used to derive the forcing functions. Validity of these forcing functions for heavy-lift and medium-lift launch vehicles was established by examining the error contributions from various sources within the wind measurement system and the application of a noise-reducing filter. A unique aspect of the method is the extraction of the relatively rapidly changing turbulent component associated with the non-persistent wind features which are expected over a given observation time period. SUBJECT TERMS AbstractA methodology is developed to derive gust forcing functions from the turbulent components of measured wind profiles. Several large sets of forcing functions were developed by extracting the short-duration, random component of measured Jimsphere wind profiles. A database consisting of Jimsphere wind soundings measured over the past three decades at the Eastern and Western Ranges of the United States was used to derive the forcing functions. Validity of these forcing functions for heavy-lift and medium-lift launch vehicles was established by examining the error contributions from various sources within the wind measurement system and the application of a noise reducing filter. A unique aspect of the method is the extraction of the relatively rapidly changing turbulent component associated with the non-persistent wind features which are expected over a given observation time period. The gust forcing functions can be used in a Monte Carlo analysis to determine launch vehicle loads for the Eastern and Western Ranges.

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“…(14) are necessary to develop empirical gust loads analysis forcing functions 2 " and to establish loads due to atmospheric turbulence. 21 ' 22 Since the gust loads analysis accounts for the turbulent components of the winds statistically, and the average boundary between the slowly-varying and turbulent components of the wind can now be defined for the ER and WR ranges, there is the possibility of retaining in the day-of-launch loads analyses only those components of the winds that are slowly varying. 21 It is suggested that, to conservatively bracket the variation of this function, the values obtained with Eq.…”

Section: Potential Usesmentioning

confidence: 99%

Identifying Slowly-Varying and Turbulent Wind Features for Flight Loads Analyses

Spiekermann¹,

Sako²,

Kabe³

1999

0

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports. 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and A methodology developed to determine the spectral boundary between the slowly-varying components and the more rapidly varying, or turbulent components, of measured wind profiles is presented. Pairs of measured wind velocity versus altitude profiles from the Eastern and Western launch ranges of the United States were used to establish the vertical wavelengths which could no longer be considered slowly varying over discrete time intervals. Analyses were performed for wind pairs that were 30, 60, 90, and 120 minutes apart. The wavelength boundary between slowly-varying and turbulent wind features as a function of time interval is presented. The results of this work make it now possible to identify and extract the slowly-varying and/or turbulent wind features, as needed for a specific day-of-launch flight loads analysis, for these two launch facilities. SUBJECT TERMS AbstractA methodology is developed to determine the spectral boundary between wind features that can be considered slowly varying, and the more rapidly-varying, or turbulent, features of measured wind profiles. Pairs of measured wind velocity versus altitude profiles from the Eastern and Western launch ranges of the United States were used to establish the vertical wavelengths which could no longer be considered slowly varying over discrete time intervals. Analyses were performed for wind pairs that were 30, 60, 90 and 120 minutes apart. The wavelength boundary between slowly-varying and turbulent wind features as a function of time interval is presented. The results of this work make it possible to identify and extract the slowly-varying and turbulent wind features at a particular launch site.

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Atmospheric flight gust loads analysis

Cited by 4 publications

References 3 publications

Derivation of Forcing Functions for Monte Carlo Atmospheric Gust Loads Analysis

Derivation of Forcing Functions for Monte Carlo Atmospheric Gust Loads Analysis

Derivation of forcing functions for Monte Carlo atmospheric gust loads analysis

Identifying Slowly-Varying and Turbulent Wind Features for Flight Loads Analyses

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